Sliding nozzle assembly

ABSTRACT

The known sliding nozzle assembly mounted to the bottom plate of metallurgical vessel such as a ladle or a tundish comprises a top nozzle, a stationary plate, a sliding plate and a collector nozzle. According to this invention, however, said stationary plate of the prior art is divided into two parts upper one of which is an upper retaining plate and lower one of which is an lower retaining plate having a plurality of running openings. The present nozzle assembly further comprises a sliding plate corresponding to the sliding plate in the conventional device provided under the lower retaining plate, a collector nozzle provided under the sliding plate and driving means for rotating the lower retaining plate and the sliding plate independently of each other, whereby to ensure a long life for the sliding nozzle assembly and prevention of any trouble due to leakage of molten steel from each contact surface of the plates.

United States Patent 1191 Yoshihara SLIDING NOZZLE ASSEMBLY [75] Inventor: Tetsuya Yoshihara, Fukuyama,

Japan [73] Assignees: Nippon Kokan Kabushiki Kaisha;

Kokankikai Kogyo Kabushiki Kaisha; Tokyo Yogyo Kabushiki Kaisha, all of Tokyo, Japan 221 Filed: Feb.ll, 1974 211 Appl. No.: 441,510

[30] Foreign Application Priority Data 3,814,326 6/1974 Bartlett 239/394 Primary ExaminerLloyd L. King Attorney, Agent, or Firm-Waters, Roditi, Schwartz &

Nissen 5 7 ABSTRACT The known sliding nozzle assembly mounted to the bottom plate of metallurgical vessel such as a ladle or a tundish comprises a top nozzle, a stationary plate, a sliding plate and a collector nozzle. According to this invention, however, said stationary plate of the prior art is divided into two parts upper one of which is an upper retaining plate and lower one of which is an lower retaining plate having a plurality of running openings. The present nozzle assembly further comprises a sliding plate corresponding to the sliding plate in the conventional device provided under the lower retaining plate, a collector nozzle provided under the sliding plate and driving means for rotating the lower retaining plate and the sliding plate independently of each other, whereby to ensure a long life for the sliding nozzle assembly and prevention of any trouble due to leakage of molten steel from each contact surface of the plates.

1 Claim, 4 Drawing Figures 922lllll6 BACKGROUND OF THE INVENTION The present invention relates to a sliding nozzle assembly mounted in the bottom plate of a metallurgical vessel such as a ladle or tundish and adapted to function as a molten steel feeding mechanism.

Generally, a known mechanism of this type comprises a stationary plate mounted on the lower surface of a top nozzle disposed at the bottom of a metallurgical vessel and provided with a single opening communieating with the top nozzle, and a refractory sliding plate mounted in close contact with the stationary plate and provided with a plurality of openings, whereby the sliding plate is moved to provide or interrupt a communication between the top nozzle and the opening in the sliding plate.

A disadvantage of this type of known mechanism is that when the sliding plate is moved to open and close the nozzle or to throttle the flow of molten steel therethrough, the peripheral edge of the opening in the sliding plate is seriously lost by melting and the molten steel enters into and solidifies in the lost portion of the opening with the result that as the sliding motion of the sliding plate is continued, the sliding surfaces of the stationary plate and the sliding plate are seriously damaged by the solidified molten steel and this eventually results in the leakage of molten steel through the sliding surfaces. The occurrence of this situation presents a very serious problem, since the leakage of the molten steel gives rise to a melting loss of the metal structure supporting the stationary plate and sliding plate assembly or endangers operating personnel.

On the other hand, the melting loss of the peripheral edge of the opening in the sliding plate naturally leads to a melting loss of the peripheral edge of the opening in the stationary plate. In this case, since the stationary plate is secured to the lower surface of the top nozzle at the bottom of the vessel, the sliding surface remote from the opening in the stationary plate is maintained in substantially undamaged condition despite the melting loss in the peripheral edge of the stationary plate opening. Therefore, when eventually the state is reached where the stationary plate and the sliding plate must be replaced, it is uneconomical to replace the stationary plate having the practically undamaged portrons.

SUMMARY OF THE INVENTION With a view to overcoming the foregoing difficulty, it is an object of the present invention to provide a sliding nozzle assembly wherein a stationary plate in the conventional device is divided by holizontal plane into two parts upper one of which is an immovable upper retaining plate and the lower one of which is a movable lower retaining plate having a plurality of openings formed therein, whereby one of the openings in the lower retaining plate is initially employed and when the upper peripheral edge of this opening is rendered inoperative due to the melting loss or wear thereof. the lower retaining plate is moved so that another opening communicates with the opening in the upper retaining plate located above, whereas when molten steel penetrates and leaks through for example the sliding surfaces of the lower retaining plate and a sliding plate corresponding to the sliding plate in the conventional devices during the pouring operation of the molten steel, the lower retaining plate is used to interrupt the communication between its opening and the opening in the upper retaining plate and thereby to ensure safety in the operation.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a longitudinal side sectional view of a sliding nozzle assembly according to an embodiment of the present invention.

FIG. 2 is a diagram useful for explaining the degree of frequency of use of the nozzle in a conventional stationary plate (2A) and sliding plate (28) assembly.

FIG. 3 is a diagram useful for explaining the wide open (3A) and fully closed (33) positions of the nozzle in the lower retaining plate used in the assembly of this invention.

FIG. 4 is a fractional sectional view showing a modification of the upper retaining plate used in the assembly of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will now be described in greater detail with reference to the illustrated embodiment.

Referring first to FIG. 1, numeral 1 designates the bottom plate of a metallurgical vessel and numeral 2 designates a top nozzle. Mounted on the lower surface of the top nozzle 2 is an upper retaining plate 3 made of refractory material and having a flat lower surface, and a lower retaining plate 4 is mounted on the lower surface of the upper retaining plate 3. The sliding plate 5 is provided with a plurality of openings 6, and 6 and it is housed in a pan-shaped rotor 8 which is provided with a gear 7 on the outer periphery thereof and which is rotatably carried on the metallurgical vessel bottom plate 1 by a spring supporting device that is not shown. The lower retaining plate 4 placed in close contact with the sliding plate 5 is provided with a flat upper surface and a plurality of openings 9, and 9 with a gear 10 mounted on the outer periphery thereof. The lower retaining plate 4 is fixedly fit in an annular member 12 formed with an engaging groove 11 in a portion of the upper surface thereof.

A transmission gear 14 for transmitting the rotation of a driving gear 13 to the gear 7 of the rotor 8, has a thickness so that it meshes either one of the rotor gear 7 and the annular member gear 10. The upper end of a supporting shaft 15 for the gear 14 is bent and extends laterally and is provided at its forward end with a lock pin 16 which fits in the engaging groove 11 in the annular member 12. A rack 17 is also formed in a portion of the upper end of the supporting shaft 15 so that the rack 17 engages with a pinion 19 mounted on the lower surface of the metallurgical vessel bottom plate 1 and provided with a handle 18. Further, in FIG. 1, numeral 20 designates collector nozzles held on the lower surface of the rotor 8, and numeral 21 designates a steel plate placed on a portion of the upper surface of the lower retaining plate 4.

With the construction described above, the operation of the sliding nozzle assembly is as follows. When molten steel is to be poured, as shown in FIG. 1, one of the openings in the lower retaining plate 4, e.g., the opening 9, is communicated with an opening 3 of the upper retaining plate 3 and then one of the openings in the slide plate 5, e.g., the opening 6, is communicated with the lower retaining plate opening 9,. Normally, when it is desired to throttle the nozzle to regulate the flow rate of molten steel, to use the other sliding plate opening 6 in place of the opening 6 or to stop the flow of molten steel, the rotation of the driving gear 13 is transmitted to the rotor 8 through the transmission gear 14. In this case, the pinion 19 is rotated by the handle 18 to lower the supporting shaft 15 of the transmission gear 14 so that the gear 14 engages with only the rotor gear 7 and it is out of engagement with the gear 10 of the annular member 12. The lowering of the supporting shaft 15 simultaneously causes the lock pin 16 to be inserted in the groove 11 of the annular member 12 with the re sult that though the lower retaining plate 4 tends to rotate due to the sliding friction caused by the rotation of the rotor 8, it is prevented from rotating since the annular member 12 is held stationary by the lock pin 16 and thus the sliding plate alone is permitted to rotate.

On the other hand, when it is judged that the melting loss of the peripheral edge of the opening 9 is such that the other opening 9 should be used in place of the former or when the melting loss of the sliding surfaces of the lower retaining plate 4 and the sliding plate 5 has reached a point where the molten steel penetrates into and leaks through the sliding surfaces, the pinion 19 is rotated to raise the supporting shaft 15 so that the transmission gear 14 comes out of engagement with the gear 7 and engages with the gear 10 of the annular member 12. When this occurs, the lock pin 16 is drawn out of the engaging groove 11 of the annular member 12 to transmit the rotation ofthe driving gear 13 to the annular member 12 with the result that the lower retaining plate 4 is rotated to a desired position and thus the opening 9 comes out of alignment with the opening 3 of the retaining plate 3.

With conventional sliding nozzle assemblies, it has been generally considered that the life of the stationary plate is one half or less as compared with that of the sliding plate. This is due to the fact that as will be seen from FIG. 2, the conventional stationary plate is provided with a single opening and thus this single opening is subjected to repeated use by the sliding movement of the sliding plate with resultant very high rate of melting loss of the opening peripheral edge. However, in the assembly of this invention, the stationary plate of conventional device is divided into two parts the upper one of which an upper retaining plate and the lower one of which a lower retaining plate so that the lower half is used as an upper sliding plate having a plurality of openings therein and adapted to be slidable as the occasion demands, whereby when one of the openings in the lower retaining plate is damaged seriously, the other opening is used and in this way the openings may be used alternately to thereby increase the life expectancy of the retaining plates as compared with the conventional stationary plate. Another advantage is that should molten steel penetrate into and leak through the sliding surfaces or any other portion, the lower retaining plate is moved so that the opening 3 in the upper retaining plate 3 is closed with the relatively less damaged portion of the upper surface of the lower retaining plate to thereby positively prevent the occurrence of any trouble due to the penetration and leakage of molten steel. Further, while, in the embodiment described above, the stationary plate of conventional device is divided into two parts and the lower one is rendered slidable, it is of course possible to apply the present invention to an assembly in which the reciprocating sliding motion is utilized. Furthermore, the upper retaining plate 3 may be formed integral with the top nozzle 2 at the bottom plate of the metallurgical vessel as shown in FIG. 4.

What is claimed is:

l. A sliding nozzle assembly mounted at the bottom plate of a metallurgical vessel for pouring molten steel therethrough comprising a top nozzle, a lower retaining plate of refractory material mounted at the lower surface of said top nozzle and having a plurality of runner openings, a sliding plate of refractory material placed beneath said lower retaining plate and having a plurality of runner openings, and driving means provided on one side of said lower retaining and sliding plates to rotate said lower retaining and sliding plates independently of each other. 

1. A sliding nozzle assembly mounted at the bottom plate of a metallurgical vessel for pouring molten steel therethrough comprising a top nozzle, a lower retaining plate of refractory material mounted at the lower surface of said top nozzle and having a plurality of runner openings, a sliding plate of refractory material placed beneath said lower retaining plate and having a plurality of runner openings, and driving means provided on one side of said lower retaining and sliding plates to rotate said lower retaining and sliding plates independently of each other. 